Our surveys of lizard populations from different life zones in Colombia have succeeded in identifying their principal Plasmodium parasites. The few remaining regions still unstudied will be visited as occasion permits. Most infected populations inhabit tropical and subtropical, dry to rain forest zones below 1,000 meters. No infections were found inreptiles from arid or desert regions, but otherwise they occur throughout the country. Host-parasite complexes at 3 sites have been sampled intensively to study their seasonal infection patterns, relation to local climate conditions, and possible impact of the infections on the populations. Unreliable museum identifications of the lizards, especially in the often-infected anole group, made clear the need for a serious taxonomic revision. This revision has been time consuming, and has delayed close study of the positive blood slides. The nearly 3,000 specimens collected (over 100 of the 140 described species) provide a solid basis for our preparation of an illustrated field guide to the Colombian lizards, which may prove to be the first such guide yet developed for tropical America. The following activities and their respective manuscripts are expected to be finished during 1979-1980: (1) completion of the guidebook to Colombian lizards; (2) confirmation of the seasonal infection patterns in gecko populations near Santa Marta, (3) teiid and iguanid populations in the eastern plains, and (4) anole populations on Barro Colorado Island, Panama; (5) description of the structure and dynamics of malaria in Iguana iguana, and (6) the intraspecific morphological variation of each of the Plasmodium species found in Colombian lizards.